The present invention relates to an elevator installation with means for driving an elevator car and a corresponding support means. The present invention additionally relates to a method for providing overrun protection in an elevator installation.
Elevator installations comprise support means so as to be able to support and set in motion an elevator car. For this purpose the support means typically runs around a drive pulley driven by a drive. In most cases at least one counterweight is provided and the elevator car and the counterweight move in opposite sense as soon as the drive sets the drive pulley in motion. The traction between the drive pulley and the support means is designed so that even when the elevator car is loaded the rotation of the drive pulley is converted, as free of slip as possible, into a movement of the support means.
With present day elevator installations the elevator cars are lighter than in the case of conventional installations. The risk therefore exists that in the event of failure of the drive control the drive pulley is driven on and an empty, or almost empty, elevator car is also then conveyed in the direction of an upper shaft end when the counterweight has already moved against a buffer and no longer contributes to moving the elevator car. A spacing between the elevator car and the shaft end therefore always has to be ensured, since this spacing defines a protective space which, for example, protects assembly personnel against being caught. Penetration of the elevator car into this protective space has to be prevented. This problem is amplified due to the fact that modern support means are provided with casings or surface profiles which, due to the high coefficients of friction, enable a high level of traction.